Transparently work around VOID and ERROR being #defined on Windows. Fixes #284.

c++/src/capnp/any.h

@@ -29,6 +29,7 @@
 #include "pointer-helpers.h"
 #include "orphan.h"
 #include "list.h"
+#include <kj/windows-sanity.h>  // work-around macro conflict with `VOID`
 
 namespace capnp {
 

c++/src/capnp/c++.capnp.h

@@ -4,6 +4,7 @@
 #pragma once
 
 #include <capnp/generated-header-support.h>
+#include <kj/windows-sanity.h>
 
 #if CAPNP_VERSION != 7000
 #error "Version mismatch between generated code and library headers.  You must use the same version of the Cap'n Proto compiler and library."

c++/src/capnp/common.h

@@ -32,6 +32,7 @@
 #include <inttypes.h>
 #include <kj/string.h>
 #include <kj/memory.h>
+#include <kj/windows-sanity.h>  // work-around macro conflict with `VOID`
 
 #if CAPNP_DEBUG_TYPES
 #include <kj/units.h>

c++/src/capnp/compat/json.capnp.h

@@ -4,6 +4,7 @@
 #pragma once
 
 #include <capnp/generated-header-support.h>
+#include <kj/windows-sanity.h>
 #if !CAPNP_LITE
 #include <capnp/capability.h>
 #endif  // !CAPNP_LITE

c++/src/capnp/compiler/capnpc-c++.c++

@@ -2980,7 +2980,8 @@ private:
           "\n"
           "#pragma once\n"
           "\n"
-          "#include <capnp/generated-header-support.h>\n",
+          "#include <capnp/generated-header-support.h>\n"
+          "#include <kj/windows-sanity.h>\n",  // work-around macro conflict with VOID
           hasInterfaces ? kj::strTree(
             "#if !CAPNP_LITE\n"
             "#include <capnp/capability.h>\n"

c++/src/capnp/compiler/grammar.capnp.h

@@ -4,6 +4,7 @@
 #pragma once
 
 #include <capnp/generated-header-support.h>
+#include <kj/windows-sanity.h>
 
 #if CAPNP_VERSION != 7000
 #error "Version mismatch between generated code and library headers.  You must use the same version of the Cap'n Proto compiler and library."

c++/src/capnp/compiler/lexer.capnp.h

@@ -4,6 +4,7 @@
 #pragma once
 
 #include <capnp/generated-header-support.h>
+#include <kj/windows-sanity.h>
 
 #if CAPNP_VERSION != 7000
 #error "Version mismatch between generated code and library headers.  You must use the same version of the Cap'n Proto compiler and library."

c++/src/capnp/dynamic.h

@@ -41,6 +41,7 @@
 #include "message.h"
 #include "any.h"
 #include "capability.h"
+#include <kj/windows-sanity.h>  // work-around macro conflict with `VOID`
 
 namespace capnp {
 

c++/src/capnp/layout.h

@@ -37,6 +37,7 @@
 #include "common.h"
 #include "blob.h"
 #include "endian.h"
+#include <kj/windows-sanity.h>  // work-around macro conflict with `VOID`
 
 #if (defined(__mips__) || defined(__hppa__)) && !defined(CAPNP_CANONICALIZE_NAN)
 #define CAPNP_CANONICALIZE_NAN 1

c++/src/capnp/persistent.capnp.h

@@ -4,6 +4,7 @@
 #pragma once
 
 #include <capnp/generated-header-support.h>
+#include <kj/windows-sanity.h>
 #if !CAPNP_LITE
 #include <capnp/capability.h>
 #endif  // !CAPNP_LITE

c++/src/capnp/rpc-twoparty.capnp.h

@@ -4,6 +4,7 @@
 #pragma once
 
 #include <capnp/generated-header-support.h>
+#include <kj/windows-sanity.h>
 
 #if CAPNP_VERSION != 7000
 #error "Version mismatch between generated code and library headers.  You must use the same version of the Cap'n Proto compiler and library."

c++/src/capnp/rpc.capnp.h

@@ -4,6 +4,7 @@
 #pragma once
 
 #include <capnp/generated-header-support.h>
+#include <kj/windows-sanity.h>
 
 #if CAPNP_VERSION != 7000
 #error "Version mismatch between generated code and library headers.  You must use the same version of the Cap'n Proto compiler and library."

c++/src/capnp/schema.capnp.h

@@ -4,6 +4,7 @@
 #pragma once
 
 #include <capnp/generated-header-support.h>
+#include <kj/windows-sanity.h>
 
 #if CAPNP_VERSION != 7000
 #error "Version mismatch between generated code and library headers.  You must use the same version of the Cap'n Proto compiler and library."

c++/src/capnp/schema.h

@@ -30,6 +30,7 @@
 #endif
 
 #include <capnp/schema.capnp.h>
+#include <kj/windows-sanity.h>  // work-around macro conflict with `VOID`
 
 namespace capnp {
 

c++/src/kj/compat/gtest.h

@@ -30,6 +30,7 @@
 //   in the constructor, teardown in the destructor.
 
 #include "../test.h"
+#include <kj/windows-sanity.h>  // work-around macro conflict with `ERROR`
 
 namespace kj {
 

c++/src/kj/debug.h

@@ -112,11 +112,7 @@
 
 #include "string.h"
 #include "exception.h"
-
-#ifdef ERROR
-// This is problematic because windows.h #defines ERROR, which we use in an enum here.
-#error "Make sure to to undefine ERROR (or just #include <kj/windows-sanity.h>) before this file"
-#endif
+#include "windows-sanity.h"  // work-around macro conflict with `ERROR`
 
 namespace kj {
 

c++/src/kj/exception.h

@@ -28,6 +28,7 @@
 #include "memory.h"
 #include "array.h"
 #include "string.h"
+#include "windows-sanity.h"  // work-around macro conflict with `ERROR`
 
 namespace kj {
 

c++/src/kj/test.h

@@ -28,6 +28,7 @@
 #include "debug.h"
 #include "vector.h"
 #include "function.h"
+#include "windows-sanity.h"  // work-around macro conflict with `ERROR`
 
 namespace kj {
 

c++/src/kj/windows-sanity.h

-// Copyright (c) 2013-2014 Sandstorm Development Group, Inc. and contributors
+// Copyright (c) 2013-2018 Sandstorm Development Group, Inc. and contributors
 // Licensed under the MIT License:
 //
 // Permission is hereby granted, free of charge, to any person obtaining a copy
@@ -19,20 +19,46 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
+// This file replaces poorly-named #defines from windows.h with properly-namespaced versions, so
+// that they no longer conflict with similarly-named identifiers in other namespaces.
+//
+// This file must be #included some time after windows.h has been #included but before any attempt
+// to use the names for other purposes. However, this can be difficult to determine in header
+// files. Typically KJ / Cap'n Proto headers avoid including windows.h at all, but may use
+// conflicting identifiers. In order to relieve application developers from the need to include
+// windows-sanity.h themselves, we would like these headers to conditionally apply the fixes if
+// and only if windows.h was already included. Therefore, this header checks if windows.h has been
+// included and only applies fixups if this is the case. Furthermore, this header is designed such
+// that it can be included multiple times, and the fixups will be applied the first time it is
+// included *after* windows.h.
+//
+// Now, as long as any headers which need to use conflicting identifier names be sure to #include
+// windows-sanity.h, we can be sure that no conflicts will occur regardless of in what order the
+// application chooses to include these headers vs. windows.h.
+
+#if !_WIN32
+
+// Not on Windows. Tell the compiler never to try to include this again.
 #pragma once
 
-#if defined(__GNUC__) && !KJ_HEADER_WARNINGS
-#pragma GCC system_header
-#endif
+#elif defined(_INC_WINDOWS)
 
-#ifndef _INC_WINDOWS
-#error "windows.h needs to be included before kj/windows-sanity.h (or perhaps you don't need either?)"
-#endif
+// We're on Windows and windows.h has been included. We need to fixup the namespace. We only need
+// to do this once, but we can't do it until windows.h has been included. Since that has happened
+// now, we use `#pragma once` to tell the compiler never to include this file again.
+#pragma once
 
 namespace win32 {
   const auto ERROR_ = ERROR;
 #undef ERROR
   const auto ERROR = ERROR_;
+
+  typedef VOID VOID_;
+#undef VOID
+  typedef VOID_ VOID;
 }
 
 using win32::ERROR;
+using win32::VOID;
+
+#endif